perfect tense + since

"I have seen her" and "I saw her" are both correct but mean different things. Use the simple past for a finished action at a specific time and the present perfect for past events that matter now, repeated experiences, or states that continue to the present.

Quick answer

Use "I saw her" (simple past) for a completed action tied to a past time. Use "I have seen her" (present perfect) for experiences, repeated events, or actions that connect to now.

Finished past time → simple past: I saw her yesterday; I saw her at 3 pm.
No finished time or link to now → present perfect: I have seen her this week; I have seen her several times.
Use since with present perfect only when it marks a start point that continues: I have known her since 2015. If you mean one meeting at a past time, use simple past: I saw her last week.

Core explanation (short)

Simple past = a finished action at a definite past time (often with a time phrase). Present perfect = a past event with present relevance or a state continuing from a start point to now.

Simple past form: I saw (past tense).
Present perfect form: I have seen (have/has + past participle).
Present perfect commonly pairs with since, for, recently, already, yet, ever.

Common traps with since and for

'Since' names a start point (since 2019, since Monday). Use it with present perfect to show continuity to now. 'For' names a duration (for three years). Don't use present perfect with finished-time words (yesterday, last week, in 2018).

Wrong: I have seen her since last week. → If you mean one meeting last week, write I saw her last week.
Wrong: I have been working here since five years. →
Correct: I have been working here for five years.

Real usage and tone (work, school, casual)

Choose the tense that matches whether you describe a completed past fact or something relevant now.

Work: I have seen the updated budget and it changes our forecast. (present relevance) - I saw the updated budget on Monday. (reports when)
School: I have seen similar research in recent journals. (experience that matters) - I saw that paper at the conference last year. (past event)
Casual: I've seen that movie before. (experience) - I saw that movie last night. (specific time)

Examples: 12 wrong/right pairs (copyable templates)

Each wrong sentence is followed by corrected options and brief notes where useful.

Work - Wrong: I have seen her in the meeting yesterday.
Right: I saw her in the meeting yesterday.
Work - Wrong: I have been collaborating with Mark since two months.
Right: I have been collaborating with Mark for two months.
Work - Wrong: I have seen the client at 3 pm last Thursday.
Right: I saw the client at 3 pm last Thursday.
School - Wrong: I have seen her at school last week.
Right: I saw her at school last week.
School - Wrong: I have been studying here since three years.
Right: I have been studying here for three years.
School - Wrong: I have seen the professor since Monday. (If you only met once on Monday.)
Right: I saw the professor on Monday. Alternate: I have seen the professor since Monday. (If meetings continued to today.)
Casual - Wrong: I have seen her yesterday at the café.
Right: I saw her yesterday at the café.
Casual - Wrong: I've seen him since the party. (If you mean one encounter at the party.)
Right: I saw him at the party.
Casual - Wrong: I have seen her since two days.
Right: I saw her two days ago. Alternate (repeated sightings): I've seen her several times over the last two days.
Work - Wrong: I have seen the report last week.
Right: I saw the report last week.
Casual - Wrong: I have seen this movie last month.
Right: I saw this movie last month.
Wrong: I have seen those changes since the meeting. (If changes happened only at the meeting.)
Right: I saw those changes at the meeting. Alternate (if changes continued): I have seen those changes since the meeting.

Rewrite help: quick templates and fixes

Checklist: 1) Is it a finished past event with a time? → simple past. 2) Is it about experience or ongoing relevance? → present perfect. 3) Is 'since' a start point? Keep present perfect. Is 'since' paired with a duration? Replace with 'for'.

Finished event template: I saw her [time]. (I saw her yesterday; I saw her at 10 am.)
Experience/relevance template: I have seen her [recently/this week/several times].
Ongoing from a start: I have known/seen/been seeing her since [date].
Change 'since' + duration → 'for' + duration: since two years → for two years.

Rewrite:
Original: I have seen her since last week. If you meant one meeting: I saw her last week. If you meant repeated meetings: I have seen her several times since last week.
Rewrite:
Original: I have seen him since two days. Fix: I saw him two days ago. Alternate (ongoing): I've seen him a few times over the last two days.
Rewrite:
Original: I have been working here since five years. Fix: I have been working here for five years.
Rewrite:
Original: I have seen the update yesterday. Fix: I saw the update yesterday.

Try your own sentence

Test the whole sentence in context. Context usually makes the correct tense clear.

Memory tricks and quick tests

Three quick proofreading checks.

Finished-time test: Add "yesterday" or a time-if it fits, use simple past.
Since-start test: If you have a clear start point (since 2018) and continuity to now, use present perfect.
Relevance test: If the sentence answers "Why does it matter now?" prefer present perfect.

Usage test: "I have seen her." Add "yesterday": "I have seen her yesterday" sounds wrong → use "I saw her yesterday."

Grammar notes: quick reference

Forms and common confusions at a glance.

Present perfect = have/has + past participle (have seen).
Simple past = past form (saw).
Present perfect continuous = have/has been + -ing (have been seeing) for repeated/ongoing actions.
Stative verbs (know, live) commonly use present perfect for continuing states: I have known her since 2012.

Note: Past perfect shows an action before another past action: By the time class started, I had seen the email.

Hyphenation & spacing (practical)

Small punctuation and spacing choices affect clarity and quick edits.

Don't insert commas inside simple time phrases: I saw her yesterday (not I saw her, yesterday).
Keep "since 2019" and "for five years" next to the verb they modify: I have lived here for five years.
Avoid stray spaces before commas or after opening quotes when copying sentences into editors.

Similar mistakes to watch for

Related tense errors to double-check when you edit.

Mixing present perfect with past perfect: Use past perfect (had + past participle) to show something happened before another past event.
Confusing present perfect and present perfect continuous: use continuous for ongoing repeated actions (I have been seeing a tutor).
Using 'since' with a duration instead of a start point: replace with 'for' for durations.

Usage: Wrong: I have seen her before the meeting. Better: I had seen her before the meeting (or I saw her before the meeting), depending on order and emphasis.

FAQ

Can I say "I have seen her yesterday"?

No. "Yesterday" is a finished time and doesn't go with present perfect. Use: I saw her yesterday.

Is "I have seen her since Monday" ever correct?

Yes-if encounters or visits continued from Monday to now. If you mean a single meeting on Monday, say: I saw her on Monday.

Which is correct: "I have seen her for two days" or "I saw her two days ago"?

"I saw her two days ago" describes a single event. "I have seen her for two days" implies repeated or ongoing sightings over that period; more natural: "I've seen her several times over the last two days."

How do I fix "since" used with a duration (e.g., "since five years")?

Replace "since" with "for" for durations: I have worked here for five years. Use "since" only with a start point: I have worked here since 2018.

What's the fastest way to check tense in my sentence?

Ask: Is the event finished at a definite past time? If yes, use simple past. If it connects to now or runs from a start point to now, use present perfect. When unsure, write both and choose the one that matches your intended meaning.

Need a quick sentence check?

Paste your sentence into a grammar checker or use the templates above to decide between "I saw her" and "I have seen her." Use the rewrites for fast fixes in emails, assignments, or messages.